Removed some unused imports

attic/archive.py

@@ -1,4 +1,4 @@
-from datetime import datetime, timedelta, timezone
+from datetime import datetime
 from getpass import getuser
 from itertools import groupby
 import errno

attic/helpers.py

@@ -5,7 +5,6 @@ import msgpack
 import os
 import pwd
 import re
-import stat
 import sys
 import time
 from datetime import datetime, timezone, timedelta